The correct program of RNA synthesis and storage during oocyte growth, as well as final accumulation of maternal factors during oocyte maturation, is essential to establish competency for meiosis and embryogenesis. However, the cellular mechanisms that impart oocyte developmental competence are unclear. My long-range goal is to understand the mechanisms of cytoplasmic maturation in mammalian oocytes in relation to developmental potential. The objective of this application is to identify molecular markers in mature oocytes that are correlated with developmental competence. The central hypothesis for the proposed research is that a differential pattern of mRNA expression exists in oocytes with good and poor developmental competence that reflects functional differences within these two classes of oocytes. The specific aim of the proposed research is to compare gene expression in oocytes with good and poor developmental potentials to elucidate mechanisms involved in the acquisition of developmental competence, using commercially available mouse microarrays. This research will establish the gene expression profile of developmentally competent oocytes, and identify changes in this profile associated with reduced developmental potential. The results obtained will significantly advance our understanding of cytoplasmic maturation in mammalian oocytes in relation to developmental potential. At the completion of the proposed research, molecular markers in oocytes and eggs that are correlated with developmental competence will be identified. These studies will lay the groundwork for future research in which specific differentially expressed genes can be targeted for research that is more detailed and further functional analysis. Of special interest will be genes whose products might be used as non-invasive markers to identify developmentally competent oocytes. The research proposed in this application is significant because it will enable us to apply the information gained to the alleviation of human infertility and development of therapies to increase developmental potential in oocytes with inherently low developmental competence.